Optical channel waveguides comprise a first material having a first index of refraction surrounded by cladding materials having lower indices of refraction. Optical energy propagates within the channel defined by the first material. One common method of manufacturing such waveguides is to deposit a strip of titanium or the like on a lithium niobate substrate and to expose the apparatus to a high temperature to cause the titanium to in-diffuse to form the channel. However, lithium niobate is not a suitable substrate for integrating semiconductor devices with the optical waveguide. Furthermore, any process which involves a high temperature in-diffusion step introduces the problem of the exposure of any devices which are integrated with the optical channel to the high temperature.
Another method of fabricating optical channel waveguides involves the preferential etching of silicon to form a V-groove into which a high index of refraction material is deposited. The masking, etching and deposition steps required for this process cannot be performed during a single pumpdown of the vacuum system. Thus, the problem of contamination of the various layers of the finished device is introduced.